Coaxial connectors have been used for many years for terminating and connecting coaxial cable to various apparatus. A typical coaxial connector is the BNC type shown in an exploded view in FIG. 1, in an assembled, partial cutaway view in FIG. 2, in an assembled, planar view in FIG. 3 and in an end view in FIG. 3A. The coaxial cable 10, commonly referred to as simply "coax", has an outer rubber or synthetic insulator 12 overlaying a braided coaxial shield 14. A central conductor 16 surrounded by another insulator 18 fits within the shield 14. The coax connector 20 includes a center electrical contact 22 having a cone-shaped rear portion 24 and a forward contact pin 26. The portion 24 is electrically insulated from the pin 26. When the contact 22 is coupled to cable 10, the shield 14 slips around the outside surface of cone portion 24 while conductor 16 is inserted into electrical connection with contact pin 26. The contact 22 is inserted into outer housing 28 and threaded ferrule 30 is screwed into the housing. A floating ferrule 32 within ferrule 30 crimps the cable 10 into fixed engagement with contact 22 upon tightening of ferrule 30 into housing 28.
When assembled properly, the contact pin 26 extends through an outer conductor spring 34 such that an end of contact pin 26 is generally coextensive with an end 36 of conductor spring 34. The conductor spring 34 encloses an insulator 38 which is coaxial with and spaced from pin 26. An outer end of insulator 38 terminates generally coextensively with conductor spring 34. The spring 34 electrically connects to shield 14 on cable 10.
Various regulations and standards apply to connector 20 including regulations and standards designed to set impedance and noise generation and introduction. Improper assembly of connector 20 can result in signal degradation and introduction of electrical noise. One area that is known to affect electrical characteristics of such coax connectors is the depth of the end of pin 26 with respect to the outer end 36 of conductor spring 34. In particular, it is generally desirable that the tip of pin 26 be about 0.030 inches below the outer end of the conductor spring 34. An exemplary specification for such distance, indicated at A in FIG. 3, is 0.030.+-.0.019 inches. In the past, small gauges, such as gauge 40 in FIG. 4, have been used to confirm proper depth of pin 26. However, such gauges are difficult to use accurately and require "feel" as well as visual acuity to check pin depth. Accordingly, it is desirable to provide an improved apparatus for accurately measuring pin depth on coax connectors.